Modular Synth Panels

I'm looking for axial polypropylene caps.  More specifically, I'm
looking to buy small quantities of 400V caps in smallish values such
as 20nF, 50nF, 100nF, 220nF, etc. I checked Mouser, Digi-Key, Allied,
and Newark.  Antique Electronic Supply sells Illinois Capacitor's MPW
series in 630V values, but they don't sell their 400V caps.  While
I've found a number of radial caps, it seems all the axial film caps
are either outrageously expensive, not available in the right values,
or both.  Any ideas??